Labels are typically applied to beverage containers and bottles filled with beverages in a continuous process by automatic labeling machines which constitute part of a rotary machine used for bottling. Poorly or slantingly applied labels can signify a deficiency which, under unfavorable conditions, can lead to shut-down of the bottling machine. To be able to continuously check for correct placement and fixation of the labels, a camera, or optionally a plurality of cameras having subsequent image analysis can be configured downstream of the labeling machine.
A labeling machine of this kind can be inferred from the German Examined Specification DE 199 11 074 B4. In the case of this known device, the analyzed images from a camera configured downstream of the labeling station are not only used for monitoring for correct placement of the labels, rather, correction signals are also generated therefrom for controlling a correction device for the particular labeling station or for synchronizing a gripper cylinder and removal elements. Thus, to a certain degree, this known system allows for correction of the label placement during continuous operation of the machine.
However, the known monitoring devices are only able to function with the desired degree of reliability when they, themselves, are not out of alignment. To correctly position the camera that is customarily used and to calibrate, respectively initialize this position, test containers can be used, for example, which have a suitable test pattern that can be recognized by the camera and used by the downstream evaluation unit to check the camera settings.
Such a test container and a test arrangement for a control device for containers is discussed in the German Patent Application DE 10 2006 022 492 A1. The test container has a plurality of uniform horizontal marking rings on the container surface that are intersected by vertical markings, thereby forming a grid-type marking structure. With the aid of this marking structure, and by using a system for precise height adjustment of the test container, the camera can be calibrated and adjusted.
Problems can always arise during operation of a labeling machine when an undetected camera misalignment either results in a failure to detect improperly applied labels or in an insufficient or even faulty correction of the setting data used for applying the labels. Often the necessity for a repeated adjustment and subsequent recalibration of the camera can only be deduced by taking precise measurements of containers provided with labels. In this case, however, a multiplicity of containers having improperly glued-on labels may have already been considered to be acceptable and fed for further processing and/or packaging.